Advances in the pathophysiology and treatment of heparin-induced thrombocytopenia.

PURPOSE OF REVIEW: To review the recent developments in understanding the pathophysiology of heparin-induced thrombocytopenia (HIT) and in applying this knowledge to the treatment of patients with suspected and proven HIT. RECENT FINDINGS: HIT pathophysiology is dynamic and complex. HIT pathophysiology is initiated by four essential components--heparin (Hep), platelet factor 4 (PF4), IgG antibodies against the Hep-PF4 complex, and platelet FcγRIIa. HIT is propagated by activated platelets, monocytes, endothelial cells, and coagulation proteins. Insights into the unique HIT antibody response continue to emerge, but without consensus as to the relative roles of B cells, T cells, and antigen-presenting cells. Platelet activation via FcγRIIa, the sine qua non of HIT, has become much better appreciated. Therapy remains challenging for several reasons. Suspected HIT is more frequent than proven HIT, because of the widespread use of Hep and the inadequacies of current diagnostic tests and scoring systems. In proven HIT, approved treatments reduce but do not eliminate thrombosis, and have substantial bleeding risk. Rational novel therapeutic strategies, directed at the initiating steps in HIT pathophysiology and with potential combinations staged over time, are in various phases of development. SUMMARY: Progress continues in understanding the breadth of molecular and cellular players in HIT. Translation to improved diagnosis and treatment is needed

Additive effects of blood donor smoking and gamma irradiation on outcome measures of red blood cell transfusion

BackgroundRecent publications have reported conflicting results regarding the role of blood donor tobacco use on hemoglobin (Hb) levels in patients after red blood cell (RBC) transfusion. We examined associations and interactions between donor, component, and recipient factors to better understand the impact of donor smoking on transfusion outcomes.Study design and methodsWe linked blood donor and component manufacturing data, including self-reported cigarette smoking, with a cohort of patients transfused RBCs between 2013 and 2016. Using multivariable regression, we examined Hb increments and subsequent transfusion requirements after single-unit RBC transfusion episodes, adjusting for donor, component, and recipient factors.ResultsWe linked data on 4038 transfusion recipients who received one or more single-unit RBC transfusions (n = 5086 units) to donor demographic and component manufacturing characteristics. Among RBC units from smokers (n = 326), Hb increments were reduced after transfusion of gamma-irradiated units (0.76 g/dL; p = 0.033) but not unirradiated units (1.04 g/dL; p = 0.54) compared to those from nonsmokers (1.01 g/dL; n = 4760). In parallel with changes in Hb levels, donor smoking was associated with the receipt of additional RBC transfusions for irradiated (odds ratio [OR], 2.49; p = 0.01) but not unirradiated RBC units (OR, 1.10; p = 0.52).ConclusionDonor smoking was associated with reduced Hb increments and the need for additional transfusions in recipients of gamma-irradiated RBC units. Additional research is needed to better understand interactions between donor, component, and recipient factors on efficacy measures of RBC transfusion

Author Correction: Convalescent plasma for hospitalized patients with COVID-19: an open-label, randomized controlled trial (Nature Medicine, (2021), 27, 11, (2012-2024), 10.1038/s41591-021-01488-2)

In the version of this Article initially published, there was an omission in the member list for the CONCOR-1 Study Group. Valérie Arsenault (Héma-Québec, Montreal, Quebec, Canada) has now been included in the CONCOR-1 Study Group in the online version of the article

automated (centrifugal) therapeutic plasma exchange option for Guillain‑Barre syndrome: A report from Calabar, Nigeria

Therapeutic plasma exchange (TPE) is performed frequently and effectively in developed countries, whereas the reverse is the case in developing countries. Guillain‑Barre syndrome (GBS), synonymous with acute inflammatory demyelinating polyneuropathy, is an important indication for TPE, but this is rarely administered in the treatment of such patients in Nigeria due to lack of such automated facility, limited expertise, and high cost. This report therefore presents an uncommon case of GBS in which automated TPE was utilized in the management, with the aims of highlighting the current status and challenges of therapeutic apheresis services in Nigeria. A 42‑year‑old male presented with rapidly progressive (in an ascending fashion) paralysis of all four limbs within 24 h without any preceding history of fever or other symptoms. Clinical examination revealed a young man, afebrile, not pale, and also not dehydrated. Central nervoussystem examination showed a conscious man, alert, and oriented in time, person, and place. There were no signs of meningeal irritation and the cranial nerves were grossly intact. There was no power in the limbs: global hypotonia and areflexia were noted on examination. However, he had intact sensory perceptions to touch and pain. Following a diagnosis of GBS, he was treated with four sessions of plasmapheresis and TPE. The TPE session was done using a discontinuous flow apheresis machine which exchanged one plasma  volume (3 L of plasma) and 5% albumin used for replacement. The patient made gradual but steady recovery as return of power to the upper limbs and trunk started by the 2nd week of treatment. TPE is an important  treatment modality in the management of GBS as well as several other conditions, and it is becoming   increasingly available in Nigeria. However, it is still grossly underutilized, thus the need for more therapeuticapheresis facilities and trained personnel, in addition to concerted efforts to subsidize the cost of accessing the  treatment.Keywords: Guillain‑Barre syndrome, therapeutic apheresis, therapeutic plasma exchang